1. Cross-reference
This application is a Continuation of International Application PCT/JP98/05118 which was filed on Nov. 13, 1998 claiming the conventional priority of Japanese patent application Nos. 9-330861 and 9-330862 filed on Nov. 14, 1997, respectively.
2. Field of the Invention
The present invention relates to an exposure apparatus and an exposure method based on the use of a reflecting type mask. In particular, the present invention relates to an exposure apparatus and a method for producing the same, as well as an exposure method to be used, for example, when a circuit device such as a semiconductor element and a liquid crystal display element is produced in accordance with a lithography step.
3. Description of the Related Art
At present, a circuit device (for example, D-RAM of 64 M (mega) bits) having a minimum line width of about 0.3 to 0.35 xcexcm is mass-produced in the production site for the semiconductor device by using a reduction projection exposure apparatus, i.e., a so-called stepper based on the use of an illumination light beam of an i-ray of a mercury lamp having a wavelength of 365 nm. Simultaneously, an exposure apparatus has been introduced in order to produce a circuit device of the next generation having a degree of integration of about 256 M bits or 1 G (giga) bits D-RAM class with a minimum line width of not more than 0.25 xcexcm.
A scanning type exposure apparatus based on the step-and-scan system is developed as an exposure apparatus for producing the next generation circuit device, in which the illumination light beam is an ultraviolet pulse laser beam having a wavelength of 248 nm radiated from a KrF excimer laser light source or an ultraviolet pulse laser beam having a wavelength of 193 nm radiated from an ArF excimer laser light source, and a mask or a reticle (hereinafter generally referred to as xe2x80x9creticlexe2x80x9d) with a depicted circuit pattern and a wafer as a photosensitive substrate are subjected to relative one-dimensional scanning with respect to a projection field of a reduction projection optical system to thereby repeat the stepping operation between shots and the scanning exposure operation for transferring the entire circuit pattern on the reticle into one shot area on the wafer.
It is certain that the degree of integration of the semiconductor device may be further increased to be high in future, and those having 1 G bits may be replaced with those having 4 G bits. In such a situation, the device rule is 0.1 xcexcm, i.e., about 100 nm L/S. There are numerous technical tasks if such a situation is dealt with the exposure apparatus which uses the illumination light beam of the ultraviolet pulse laser beam having the wavelength of 193 nm as described above. The resolution of the exposure apparatus to represent the device rule (practical minimum line width) is generally represented by the following expression (1) with the exposure wavelength xcex and the numerical aperture N.A. of the projection optical system.
(Resolution)=kxc2x7xcex/N.A.xe2x80x83xe2x80x83(1)
In the expression, k represents a positive constant called xe2x80x9ck factorxe2x80x9d of not more than 1, and it differs depending on, for example, the characteristic of the resist to be used.
As clarified from the foregoing expression (1), it is extremely effective to decrease the wavelength xcex in order to enhance the resolution. Therefore, recently, the development is started for an EUV exposure apparatus which uses, as an exposure light beam, a light beam in the soft X-ray region having a wavelength of 5 to 15 nm (in this specification, the light beam is referred to as xe2x80x9cEUV (Extreme Ultra Violet) light beamxe2x80x9d as well). Such an EUV exposure apparatus attracts the attention as a hopeful candidate for the next generation exposure apparatus having a minimum line width of 100 nm.
The EUV exposure apparatus generally uses a reflecting type reticle. An illumination light beam is radiated obliquely onto the reflecting type reticle. A reflected light beam from the reticle surface is projected onto a wafer via a projection optical system. Thus, a pattern in an illumination area on the reticle is transferred onto the wafer. In the case of the EUV exposure apparatus, the scanning exposure method is adopted as follows, in order to transfer the pattern by utilizing only a portion of the projection optical system in which the image formation performance is excellent. That is, a ring-shaped illumination area is set on the reticle, and the entire surface of the pattern on the reticle is successively transferred onto the wafer via the projection optical system by relatively scanning the reticle and the wafer with respect to the projection optical system.
The reason why the reflecting type reticle is used is as follows. That is, there is no substance for producing a reticle which efficiently transmit the light without any absorption at the wavelength (5 to 15 nm) of light used for the EUV exposure apparatus. Further, it is also difficult to prepare a beam splitter. Therefore, it is necessary that the illumination light beam is radiated obliquely with respect to the reticle.
For this reason, the side of the reticle is non-telecentric. The displacement of the reticle in the direction along the optical axis appears as the change in magnification in the longitudinal direction and as the change in position in the transverse direction of the ring-shaped exposure area on the wafer (area on the wafer corresponding to the ring-shaped illumination area on the reticle).
Explanation will be made referring to specified numerical values. It is assumed that an EUV light beam having a wavelength of 13 nm is used as an exposure light beam to design a projection optical system having a resolution of 100 nm L/S.
The foregoing expression (1) can be converted into the following expression (2).
N.A.=kxc2x7xcex/(resolution)xe2x80x83xe2x80x83(2)
It is now assumed that k=0.8 is given. According to the expression (2), it is comprehensive that N.A. necessary to obtain the resolution of 100 nm L/S is N.A.=0.104≈0.1. Of course, this N.A. represents a value on the wafer side, which is different from N.A. on the reticle side.
It is now assumed that the projection magnification of the projection optical system is 4:1 which is generally used for the conventional far ultraviolet ray exposure apparatus (DUV exposure apparatus) which uses the exposure light beam of i-ray, g-ray, KrF excimer laser beam, or ArF excimer laser beam. If N.A. is 0.1 on the wafer side, N.A. on the reticle side is xc2xc of this value, i.e., 0.025. This fact means the fact that the illumination light beam radiated onto the reticle has a broadening of an angle of about xc2x125 mrad with respect to the main ray of light. Therefore, in order not to superimpose the incoming light beam an the reflected light beam with each other, it is necessary that the angle of incidence is not less than 25 mrad at the minimum.
For example, with reference to FIG. 16, it is assumed that the angle of incidence xcex8 (=outgoing angle xcex8) is 50 mrad. The lateral discrepancy xcex5 of the circuit pattern depicted on the reticle R with respect to the displacement AZ in the Z direction of the pattern plane of the reticle R (hereinafter appropriately referred to as xe2x80x9cdisplacement of the reticle in the Z directionxe2x80x9d as well) is represented by the following expression (3).
xcex5=xcex94Zxc2x7tan xcex8xe2x80x83xe2x80x83(3)
According to the expression (3), the following fact is comprehensible. That is, for example, if the reticle R is displaced by 1 xcexcm in the vertical direction (Z direction) in FIG. 16, the lateral discrepancy of the image on the reticle pattern plane is about 50 nm. On the wafer, the image shift occurs in an amount of xc2xc of this value, i.e., 2.5 nm. It is also approved that the overlay error (superimposing error), which is allowable in the semiconductor process with the device rule of 100 nm L/S, is not more than 30 nm. The occurrence of the overlay error of 12.5 nm, which is caused by only the displacement of the reticle in the Z direction, is considered to be extremely severe. That is, the overlay error may be caused in an amount of about 10 nm respectively by other factors including, for example, the positioning accuracy (alignment accuracy) between the reticle and the wafer, the positioning accuracy of the wafer stage including the so-called stepping accuracy, and the distortion of the projection optical system.
The displacement of the reticle in the Z direction is also caused by the parallelism of the reticle and the flatness of the reticle holder for supporting the reticle. Therefore, it is now urgent to develop the technique to reduce the overlay error caused by the displacement of the reticle in the Z direction as described above.
The material, which has been developed until the present for the reflective film to be formed on the pattern plane of the reflecting type reticle, has a reflectance of about 70% at most. For this reason, the remain of 30% is absorbed, and it is converted into heat, resulting in the increase in temperature of a mirror (reflecting optical element) for constructing the reflecting optical system. In the worst case, the mirror is greatly deformed due to the increase in temperature, making it impossible to maintain a sufficient image formation characteristic. Therefore, in the conventional EUV exposure apparatus, the heat of the mirror is released by applying a forcible cooling means disposed on the back surface of the mirror, for example, by applying the liquid cooling or the cooling based on a Peltier element.
In this case, those assumed as the material for the mirror include low expansion glass and metal. The low expansion glass has an extremely small coefficient of linear expansion with respect to the temperature change. Therefore, the displacement amount thereof does not deteriorate the image formation performance with respect to a considerable degree of the temperature change. However, there is a certain limit. Therefore, it is desirable to perform the cooling.
However, the following inconvenience arises, because the low expansion glass has an extremely low coefficient of thermal conductivity. That is, in the case of the technique in which the back surface side of the mirror is merely cooled as described above, a lot of time is required until the heat generated on the front surface of the mirror is transmitted to the back surface. As a result, a temperature gradient arises from the front surface of the mirror to the back surface. It is impossible to sufficiently cool the front surface of the mirror, i.e., the reflecting surface which is most important. Consequently, the reflecting surface is deformed, and the image formation characteristic of the projection optical system is deteriorated. Therefore, it is feared that the image of the pattern transferred onto the substrate (hereinafter referred to as xe2x80x9ctransferred imagexe2x80x9d as well) may be deteriorated.
The deterioration of the transferred image may be also caused by the thermal variation (variation of radiation) due to the absorption of the illumination light beam by the mask on which the pattern is formed.
The present invention has been made under the circumstances as described above, a first object of which is to provide an exposure apparatus, especially an exposure apparatus including a reflecting optical system as a projection optical system which makes it possible to improve the overlay accuracy of the pattern during exposure.
A second object of the present invention is to provide an exposure method which makes it possible to improve the overlay accuracy of the pattern during exposure.
A third object of the present invention is to provide an exposure apparatus, especially an exposure apparatus including a reflecting optical system as a projection optical system which makes it possible to effectively suppress the deterioration of the transferred image resulting from the variation of radiation of a mask or a projection optical system caused by radiation of an illumination light beam (hereinafter referred to as xe2x80x9cvariation of radiationxe2x80x9d).
According to a first aspect of the present invention, there is provided an exposure apparatus for transferring a pattern formed on a reflecting type mask (R) onto a substrate (W), the exposure apparatus comprising a projection optical system (PO) provided with a reflecting type optical system which projects the pattern onto the substrate (W); a mask stage (RST) which holds the mask; a substrate stage (WST) which holds the substrate; an illumination system (12, 30, M, 44) which radiates an exposing illumination light beam (EL) onto the mask at a predetermined angle of incidence with respect to a pattern plane of the mask; and a stage control system (80, 34, 62) which synchronously moves the mask stage and the substrate stage in a second axis direction perpendicular to a first axis direction, while adjusting a position of the mask in the first axis direction which is a direction of an optical axis of the projection optical system, on the basis of predetermined adjusting position information, in order to transfer the pattern on the mask illuminated with the exposing illumination light beam onto the substrate via the projection optical system.
According to the exposure apparatus of the present invention, when the exposing illumination light beam is radiated at the predetermined angle of incidence onto the pattern plane of the mask by the illumination system, the illumination light beam is reflected by the pattern plane of the mask. The reflected exposing illumination light beam is projected onto the substrate by the projection optical system composed of the reflecting optical system. The pattern in the area on the mask, which is illuminated with the illumination light beam, is transferred onto the substrate. When the mask pattern is transferred, the stage control system is operated such that the mask stage and the substrate stage are synchronously moved in the second axis direction perpendicular to the first axis direction, while adjusting the position of the mask in the first axis direction as the direction of the optical axis of the projection optical system on the basis of the predetermined adjusting position information. Accordingly, the entire surface of the pattern on the mask is successively transferred onto the substrate in accordance with the scanning exposure. During this process, the position of the mask in the direction (first axis direction) of the optical axis of the projection optical system is adjusted on the basis of the adjusting position information. Therefore, although the mask side of the projection optical system is non-telecentric, it is possible to effectively suppress the occurrence of the magnification error and the positional discrepancy in the transferred image of the pattern on the substrate due to the displacement of the mask in the direction of the optical axis. As a result, it is possible to improve the overlay accuracy.
In the exposure apparatus described above, the adjusting position information includes first adjusting position information and second adjusting position information corresponding to a movement direction of the mask stage (RST) on the second axis; and the stage control system (80, 34, 62) may adjust the position of the mask in the first axis direction by using the adjusting position information corresponding to the movement direction, of the first adjusting position information and the second adjusting position information for each movement direction of the mask stage during the synchronous movement of the mask stage and the substrate stage (WST). The exposure apparatus is effective for the exposure apparatus of the so-called alternate scan type in which when the mask stage is moved to perform the scanning exposure, the scanning exposure is executed not only when the mask stage is moved from one side to the other side in the scanning direction but also when the mask stage is moved in a direction opposite to the above. That is, the stage control system adjusts the position of the mask in the first axis direction by using the adjusting position information corresponding to the movement direction, of the first adjusting position information and the second adjusting position information for each movement direction of the mask stage during the synchronous movement of the mask stage and the substrate stage. Therefore, even when the positional displacement in the first axis direction during the synchronous movement differs depending on, for example, any mechanical factor (movement characteristic of the stage) between the movement of the mask stage from one side to the other side in the second axis and the movement from the other side to one side, the position of the mask in the first axis direction can be adjusted highly accurately without being affected thereby. It is possible to effectively suppress the occurrence of the magnification error and the positional discrepancy in the transferred image of the pattern on the substrate due to the displacement of the mask in the direction of the optical axis.
In such an arrangement, for example, the adjusting position information may be previously measured information. In this arrangement, the adjustment can be made in accordance with, for example, the feedforward control on the basis of the previously measured information without measuring the displacement of the mask in the first axis direction during the synchronous movement of the mask stage and the substrate stage. Therefore, the adjusting error scarcely occurs due to any control delay upon the adjustment. Further, it is possible to use a simple constitutive component for adjusting the position of the mask in the first axis direction.
However, it is also preferable that when the exposure apparatus further comprises a measuring unit (RIFZ) which measures the position of the mask (R) in the first axis direction, then the stage control system (80, 34, 62) measures the adjusting position information by using the measuring unit during the synchronous movement of the mask stage (RST) and the substrate stage (WST), and it adjusts the position of the mask in the first axis direction by using the adjusting position information.
In this arrangement, a variety of measuring units are conceived as the measuring unit. For example, it is also preferable that the measuring unit is an interferometer (RIFZ) which measures the position of the mask in the first axis direction by radiating a measuring beam perpendicularly onto the mask and receiving a reflected light beam therefrom. In this arrangement, it is possible to measure and adjust the position of the mask in the direction of the optical axis during the synchronous movement highly accurately (for example, at an accuracy of not more than several nm to 1 nm) without affecting the exposing illumination light beam coming into the pattern plane on the mask at a predetermined angle of incidence and being reflected by the same outgoing angle as that of the angle of incidence, while the measuring beam o f the interferometer is not affected by the exposing illumination light beam.
In this arrangement, there is no special limitation concerning the position of radiation of the measuring beam radiated from the interferometer onto the mask and the number of measuring beams. However, for example, it is desirable that the interferometer (RIFZ) radiates at least two measuring beams onto an irradiated area (IA) of the mask (R) to be irradiated with the exposing illumination light beam, and it measures the position of the mask (R) in the first axis direction for each irradiated position of each of the measuring beams. In this arrangement, the two measuring beams are radiated by the interferometer onto the irradiated area of the exposing illumination light beam as the objective area for the pattern transfer at every moment. The position of the mask in the first axis direction is measured at each position. Therefore, as a result, it is possible to adjust not only the position in the first axis direction but also the inclination in the objective area for the pattern transfer on the mask at every moment on the basis of the most accurate measured data. Consequently, it is possible to further improve the overlay accuracy.
In the exposure apparatus described above, the interferometer has the following feature. That is, the interferometer radiates the measuring beam onto different positions of the mask in the second axis direction, and it measures the position of the mask in the first axis direction for each irradiated position of the measuring beam. In this arrangement, it is possible to adjust the positional discrepancy in the direction of the optical axis and the inclination discrepancy of the mask during the synchronous movement of the mask stage and the substrate stage at least for the second axis direction (direction of the synchronous movement).
In the exposure apparatus described above, it is also preferable that the interferometer (RIFZ) has a reference mirror fixed to the projection optical system (PO), and a main interferometer body arranged at a position separated from the projection optical system. In this arrangement, the main interferometer body is disposed at the position separated from the projection optical system. Therefore, it is possible to avoid any bad influence on optical characteristics of the projection optical system or various sensors such as an alignment sensor and a focus sensor fixed thereto, which would be otherwise caused by the heat generated by the main interferometer body.
In the exposure apparatus described above, it is also preferable that the stage control system (80, 34, 62) adjust the position of the mask in the first axis direction in accordance with feedforward control by using the measured adjusting position information. Alternatively, it is also preferable that the stage control system adjust the position of the mask in the first axis direction in accordance with feedback control by using the measured adjusting position information. In the case of the former, it is necessary for the stage control system to perform the so-called pre-reading control in order to measure the position of the mask in the direction of the optical axis before the objective area for the pattern transfer at every moment on the mask arrives at the irradiated area to be irradiated with the exposing illumination light beam. However, the position of the mask in the first axis direction can be adjusted by means of the feedforward control on the basis of the measured information. Therefore, the control delay scarcely occurs when the adjustment is performed. In the case of the latter, it is probable that the control delay occurs as compared with the former case. However, in addition to the fact that the pre-reading control is unnecessary, it is possible to adjust the position of the mask in the first axis direction with a higher degree of accuracy.
The exposure apparatus may further comprise a slit plate (44) arranged closely to the pattern plane of the mask (R) and including a first slit (44a) which defines a first illumination area (IA) on the mask to be irradiated with the exposing illumination light beam and a second slit (44b) which defines a second illumination area to be irradiated with the exposing illumination light beam at a mark (for example, RM1, RM4) portion formed on the mask; and a swinging mechanism (46) which switches the slit plate (44) between a first position for radiating the exposing illumination light beam onto the first slit (44a) and a second position for radiating the exposing illumination light beam onto the second slit (44b). According to this arrangement, the swinging mechanism switches the slit plate to the first position during the exposure so that the exposing illumination light beam may be radiated onto the first slit for defining the first illumination area on the mask. The swinging mechanism switches the slit plate to the second position during the position adjustment (alignment) for the mask so that the exposing illumination light beam may be radiated onto the second slit for defining the second illumination area for radiating the exposing illumination light beam onto the mark portion formed on the mask. Accordingly, the appropriate illumination area can be set during the exposure and during the alignment respectively by using the identical slit plate. It is unnecessary to provide slit plates depending on the respective purposes.
In the exposure apparatus described above, the mask stage (RST), the substrate stage (WST), and the projection optical system (PO) may be supported by different support members; and the apparatus may further comprise an interferometer system (70) which measures positions of the mask stage and the substrate stage in a plane including the second axis perpendicular to the first axis. In this arrangement, the interferometer system may measure relative positions of the mask stage and the substrate stage in the plane including the second axis perpendicular to the first axis with respect to the member for supporting the projection optical system. According to this arrangement, although the mask stage, the substrate stage, and the projection optical system are supported by the different support members, the positions of the mask stage and the substrate stage can be managed on the basis of the member for supporting the projection optical system, because the interferometer system measures the relative positions of the mask stage and the substrate stage in the plane including the second axis perpendicular to the first axis with respect to the member for supporting the projection optical system. Therefore, no inconvenience arises at all. That is, the mask stage, the substrate stage, and the projection optical system are not mechanically connected. Therefore, the image formation characteristics of the projection optical system are not badly affected by the reaction force caused by the rate of acceleration or deceleration during the movement of the mask stage and the substrate stage and by the vibration of the support members for the respective stages. Further, the reaction force caused by the rate of acceleration or deceleration during the movement of one of the stages does not badly affect the behavior of the other stage via the support member.
In the exposure apparatus described above, the exposing illumination light beam (EL) may be a light beam in a soft X-ray region; and the apparatus may further comprise, on the substrate stage (WST), a spatial image-measuring instrument (FM) which includes a fluorescence-generating substance (63), an aperture (SLT) formed on a surface thereof by a thin film of a reflective layer (64) or an absorbing layer for the exposing illumination light beam, and a photoelectric converter element (PM) which photoelectrically converts light generated by the fluorescence-generating substance when the exposing illumination light beam arrives at the fluorescence substance via the aperture. According to this arrangement, the apparatus further comprises, on the substrate stage, the spatial image-measuring instrument including the fluorescence-generating substance, the aperture formed on the surface thereof by the thin film of the reflective layer or the absorbing layer for the exposing illumination light beam, and the photoelectric converter element for photoelectrically converting the light generated by the fluorescence-generating substance when the exposing illumination light beam arrives at the fluorescence substance via the aperture. Therefore, usually, although there is no substance which transmits the light in the soft X-ray region as described above, the spatial image can be measured by using the exposing illumination light beam even when such a light beam is used as the exposing illumination light beam. Therefore, for example, it is possible to easily determine the projection position of the mask pattern on the substrate stage by using the spatial image-measuring instrument.
In the exposure apparatus described above, it is desirable that when the exposing illumination light beam (EL) is a light beam in a soft X-ray region; the pattern on the mask (R) is formed by applying a substance for absorbing the illumination light beam, onto a reflective layer for reflecting the exposing illumination light beam. In this arrangement, the pattern is formed (subjected to patterning) with the absorbing substance for the exposing illumination light beam. Therefore, unlike the case in which a multilayer film is subjected to patterning as a substance for reflecting the light beam in the soft X-ray region as the exposing illumination light beam, it is possible to repair the pattern in the case of failure. When the material for the absorbing substance is appropriately selected, it is possible to set a substantially identical reflectance for the reflective layer and the absorbing substance for the exposing illumination light beam with respect to the measuring beam (for example, light in the visible region) of the interferometer. It is possible to measure the position of the mask in the direction of the optical axis with a substantially identical accuracy over the entire surface on the mask.
As described in the second specified embodiment of the present invention, the exposure apparatus according to the first aspect of the present invention may further comprise a common base board which movably supports the mask stage and the substrate stage, and a surface plate which movably supports the base board, wherein the base board is movable in response to reaction force generated by movement of at least one stage of the mask stage and the substrate stage. In this arrangement, even when the scanning exposure is executed to perform the exposure while synchronously moving the mask stage and the substrate stage with respect to the illumination light beam, it is possible to suppress the vibration of the exposure apparatus based on the unbalanced load generated by the movement of the stage.
In the exposure apparatus according to the first aspect of the present invention, it is also preferable that the reflecting optical system includes a plurality of mirrors, the apparatus further comprises a heat exchanger, for example, a heat pipe which adjusts temperature of at least one of the mirrors, and the heat exchanger is installed on a non-irradiated area of a reflecting surface of at least one of the mirrors. Such a heat exchanger may be applied to exposure apparatuses according to second to fourth aspects and a seventh aspect of the present invention described later on.
According to a second aspect of the present invention, there is provided an exposure apparatus for transferring a pattern on a mask (R) onto a substrate (W), the exposure apparatus comprising an illumination optical system (PRM, IM, 30, M, 44) which has an optical axis inclined with respect to a first direction perpendicular to the mask and which radiates an illumination light beam onto the mask; a projection optical system (PO) which projects, onto the substrate, the illumination light beam reflected by the mask; a driving unit (RST, WST, 80, 34, 62) which synchronously moves the mask and the substrate at a velocity ratio corresponding to a magnification of the projection optical system; and a correcting unit (80, 34, RST) which corrects an image magnification error of the pattern by relatively moving the mask in the first direction with respect to the projection optical system during the synchronous movement.
According to the exposure apparatus concerning the second aspect, the illumination light beam in the direction of the optical axis, which is inclined with respect to the first direction perpendicular to the mask, is radiated from the illumination optical system. That is, the illumination light beam from the illumination optical system is radiated in the oblique direction onto the mask. The illumination light beam is reflected by the mask plane, the reflected light beam is projected onto the substrate by the aid of the projection optical system, and the pattern on the mask illuminated with the illumination light beam is transferred onto the substrate. Upon the transfer of the mask pattern, the driving unit is operated to synchronously move the mask and the substrate at the velocity ratio corresponding to the magnification of the projection optical system. During the synchronous movement, the correcting unit is operated to relatively move the mask in the first direction with respect to the projection optical system in order to correct the image magnification error of the pattern. Accordingly, the entire surface of the pattern on the mask is successively transferred onto the substrate in accordance with the scanning exposure. During this process, the correcting unit is operated to relatively move the mask in the first direction with respect to the projection optical system in order to correct the image magnification error of the pattern. Therefore, it is possible to effectively suppress the occurrence of the magnification error in the transferred image of the pattern on the substrate due to the displacement of the mask in the direction of the optical axis. As a result, it is possible to improve the overlay accuracy.
In this arrangement, it is also preferable that the illumination optical system (PRM, IM, 30, M, 44) radiates, as the illumination light beam (EL), an EUV light beam having a wavelength of 5 to 15 nm onto the mask (R); and the projection optical system (PO) is composed of only a plurality of reflecting optical elements. In this arrangement, the pattern on the mask is transferred onto the substrate via the projection optical system composed of only the reflecting optical elements by using the EUV light beam as the exposing illumination light beam. Therefore, it is possible to highly accurately transfer an extremely fine pattern, for example, a pattern of 100 nm L/S.
In the exposure apparatus described above, it is also preferable that when the correcting unit (80, RST, 34, RIFZ) has a measuring unit (RIFZ) which measures a position of the mask (R) in the first direction, the mask is moved on the basis of an output of the measuring unit.
According to a third aspect of the present invention, there is provided an exposure apparatus for transferring a pattern on a mask (R) onto a substrate (W), the exposure apparatus comprising an illumination optical system (PRM, IM, 30, M, 44) which radiates, onto the mask, an illumination light beam having a main light beam which is inclined with respect to a first direction perpendicular to the mask (R); a projection optical system (PO) which projects, onto the substrate, the illumination light beam outgoing from the mask; a driving unit (RST, WST, 80, 34, 62) which synchronously moves the mask and the substrate at a velocity ratio corresponding to a magnification of the projection optical system; and a correcting unit (80, RST, 34) which compensates change in image magnification of the pattern caused by the movement of the mask.
According to the exposure apparatus concerning the third aspect, the illumination optical system irradiates the mask with the illumination light beam having the main light beam which is inclined with respect to the first direction perpendicular to the mask. That is, the illumination light beam from the illumination optical system is radiated in the oblique direction onto the mask. The illumination light beam outgoing from the mask, which has the main light beam inclined with respect to the first direction perpendicular to the mask, is projected by the projection optical system onto the substrate. The pattern on the mask, which is irradiated with the illumination light beam, is transferred onto the substrate. During the transfer of the mask pattern, the driving unit is operated to synchronously move the mask and the substrate at the velocity ratio corresponding to the magnification of the projection optical system. The correcting unit compensates the change in image magnification of the pattern caused by the movement of the mask during the synchronous movement. Therefore, the entire surface of the pattern on the mask is successively transferred onto the substrate in accordance with the scanning exposure. During this process, the image magnification error of the pattern is compensated by the correcting unit. Accordingly, it is possible to effectively suppress the occurrence of the magnification error in the transferred image of the pattern on the substrate due to the movement of the mask. As a result, it is possible to improve the overlay accuracy.
In the exposure apparatus according to the third aspect, it is also preferable that the mask (R) is a reflecting type mask; the illumination optical system (PRM, IM, 30, M, 44) radiates, as the illumination light beam, an EUV light beam having a wavelength of 5 to 15 nm onto the mask; and the projection optical system (PO) is composed of only a plurality of reflecting optical elements (M1 to M4). In this arrangement, the pattern on the mask is transferred onto the substrate via the projection optical system composed of only the reflecting optical elements by using the EUV light beam as the exposing illumination light beam. Therefore, it is possible to highly accurately transfer an extremely fine pattern, for example, a pattern of 100 nm L/S.
In the exposure apparatus according to the third aspect described above, it is also preferable that the correcting unit (RST, 80, 34) includes a driving member (RST, 34) which moves the mask (R) in the first direction on an object plane side of the projection optical system during the synchronous movement. In this arrangement, it is sufficient that the driving member moves the mask in the first direction on the object plane side of the projection optical system during the synchronous movement. However, for example, it is also preferable that the driving member relatively inclines the mask with respect to the object plane of the projection optical system. In this arrangement, in addition to the movement of the mask in the first direction on the object plane side of the projection optical system by the driving member during the synchronous movement, it is also possible to adjust the inclination of the projection optical system with respect to the object plane. Therefore, although the object plane side of the projection optical system is non-telecentric, it is possible to effectively suppress the occurrence of the magnification error and the positional discrepancy in the transferred image of the pattern on the substrate due to the displacement of the mask in the direction of the optical axis. As a result, it is possible to improve the overlay accuracy.
According to a fourth aspect of the present invention, there is provided an exposure apparatus for transferring a pattern on a mask (R) onto a substrate (W), the exposure apparatus comprising an illumination optical system (PRM, IM, 30, M, 44) which radiates, onto the mask, an illumination light beam inclined with respect to a perpendicular line of the mask; and a projection optical system (PO) which projects, onto the substrate, the illumination light beam reflected by the mask; wherein the illumination optical system has a field diaphragm (44) which arranged adjacent to an incoming side of the illumination light beam with respect to the mask and which defines an irradiated area of the illumination light beam on the mask, and the field diaphragm adjusts at least one of a shape, a size, and a position of the illumination area. According to this aspect, the illumination light beam, which is inclined with respect to the perpendicular line of the mask, is radiated from the illumination optical system. That is, the illumination light beam is radiated from the illumination optical system obliquely with respect to the mask. The illumination light beam, which is reflected by the mask, is projected onto the substrate by the aid of the projection optical system. Thus, the pattern on the mask is transferred onto the substrate. In this arrangement, the illumination optical system has the field diaphragm arranged closely to the incoming side of the illumination light beam with respect to the mask, for defining the irradiated area of the illumination light beam on the mask. The field diaphragm is used to adjust at least one of the shape, the size, and the position of the illumination area. Therefore, the degree of freedom of the cross-sectional configuration of the illumination light beam radiated from the illumination optical system to the mask is increased as compared with a case in which there is no field diaphragm. Accordingly, it is possible to improve the degree of freedom of the design of the optical element for constructing the illumination optical system. Especially, when the field diaphragm is used to adjust the position of the illumination area of the illumination light beam on the mask, it is possible to use the identical illumination light beam for other purposes including, for example, the exposure and the detection of the mark position.
In the apparatus according to the fourth aspect, it is desirable that the field diaphragm (44) has a first aperture (44a) which radiates the illumination light beam (EL) onto a part of the pattern and a second aperture (44b) which radiates the illumination light beam onto a mark (for example, RM1 and RM2) formed on the mask; and the apparatus further comprises a switching mechanism (46) which switches the first aperture and the second aperture. In this arrangement, the swinging mechanism is operated as follows. That is, the field diaphragm is switched to use the first aperture during the exposure so that the illumination light beam may be radiated onto the part of the pattern on the mask. During the position adjustment (alignment) for the mask, the field diaphragm is switched to use the second aperture so that the illumination light beam may be radiated onto the mark formed on the mask. Accordingly, it is possible to set the suitable illumination area during the exposure and during the alignment respectively by using the identical field diaphragm.
According to a fifth aspect of the present invention, there is provided an exposure method for transferring a pattern formed on a mask onto a substrate via a projection optical system (PO) while synchronously moving the mask (R) and the substrate (W), the exposure method comprising preparing a reflecting type mask as the mask (R); using a reflecting optical system as the projection optical system (PO); and transferring the pattern on the mask illuminated with an exposing illumination light beam onto the substrate via the projection optical system by radiating the exposing illumination light beam at a predetermined angle of incidence xcex8 with respect to a pattern plane of the mask; wherein the mask and the substrate are synchronously moved in a second axis direction perpendicular to a first axis direction which is a direction of an optical axis of the projection optical system while adjusting a position of the mask (R) in the first axis direction on the basis of predetermined adjusting position information.
According to this method, when the pattern on the mask illuminated with the exposing illumination light beam is transferred onto the substrate via the projection optical system by radiating the exposing illumination light beam at the predetermined angle of incidence with respect to the pattern plane of the mask, the mask and the substrate are synchronously moved in the second axis direction perpendicular to the first axis direction, while adjusting the position of the mask in the first axis direction as the direction of the optical axis of the projection optical system on the basis of the predetermined adjusting position information. Therefore, the entire surface of the pattern on the mask is successively transferred onto the substrate in accordance with the scanning exposure. During this process, the position of the mask in the direction of the optical axis of the projection optical system (first axis direction) is adjusted on the basis of the adjusting position information. Therefore, although the side on the mask of the projection optical system (reflecting optical system) is non-telecentric, it is possible to effectively suppress the occurrence of the magnification error and the positional discrepancy in the transferred image of the pattern on the substrate due to the displacement of the mask in the direction of the optical axis. As a result, it is possible to improve the overlay accuracy.
In this method, it is also preferable that the adjusting position information includes first adjusting position information and second adjusting position information corresponding to a movement direction of the mask (R) on the second axis; and the position of the mask in the first axis direction is adjusted by using the adjusting position information corresponding to the movement direction, of the first adjusting position information and the second adjusting position information for each movement direction of the mask during the synchronous movement of the mask (R) and the substrate (W). In this process, the position of the mask in the first axis direction is adjusted by using the adjusting position information corresponding to the movement direction, of the first adjusting position information and the second adjusting position information for each movement direction of the mask during the synchronous movement of the mask and the substrate. Accordingly, even when the positional displacement in the first axis direction during the synchronous movement differs depending on, for example, any mechanical factor (movement characteristic of the stage) between the movement of the mask from one side to the other side along the second axis and the movement from the other side to one side, the position of the mask in the first axis direction can be adjusted highly accurately without being affected thereby. It is possible to effectively suppress the occurrence of the magnification error and the positional discrepancy in the transferred image of the pattern on the substrate due to the displacement of the mask in the direction of the optical axis.
In the exposure method described above, it is also preferable that the adjusting position information is previously measured information. Alternatively, it is also preferable that the adjusting position information is measured during the synchronous movement of the mask and the substrate, and the position of the mask in the first axis direction is adjusted by using the adjusting position information. In the case of the former, the adjustment can be made in accordance with, for example, the feedforward control on the basis of the previously measured information without measuring the displacement of the mask in the first axis direction during the synchronous movement of the mask and the substrate. Therefore, the adjusting error scarcely occurs due to any control delay upon the adjustment. Further, it is possible to use a simple constitutive component for adjusting the position of the mask in the first axis direction. In the case of the latter, the position of the mask in the first axis direction can be adjusted highly accurately in accordance with the feedback control by using the information measured during the synchronous movement.
According to a sixth aspect of the present invention, there is provided an exposure method for transferring a pattern on a mask (R) onto a substrate (w) via a projection optical system (PO), the exposure method comprising radiating an illumination light beam having a main light beam inclined with respect to a direction perpendicular to the mask; relatively moving the substrate with respect to the illumination light beam reflected by the mask to pass through the projection optical system in synchronization with relative movement of the mask with respect to the illumination light beam; and compensating change of an image magnification of the pattern caused by the synchronous movement of the mask and the substrate. The phrase xe2x80x9cchange of an image magnification of the pattern caused by the synchronous movement of the mask and the substratexe2x80x9d herein means the change of the image magnification of the pattern caused by the movement of the mask during the synchronous movement, principally by the movement in the direction of the optical axis of the projection optical system.
According to the method concerning the sixth aspect, the change of the image magnification of the pattern caused by the synchronous movement of the mask and the substrate is compensated. Therefore, although the side of the object plane of the projection optical system is non-telecentric, it is possible to effectively suppress the occurrence of the magnification error and the positional discrepancy in the transferred image of the pattern on the substrate due to the displacement of the mask in the direction of the optical axis. As a result, it is possible to improve the overlay accuracy.
According to a seventh aspect of the present invention, there is provided an exposure apparatus for transferring a pattern on a mask (R) onto a substrate (W), the exposure apparatus comprising an illumination optical system (PRM, IM, 30, M, 44) which obliquely radiates an illumination light beam onto a pattern plane of the mask; a projection optical system (PO) which projects the illumination light beam outgoing from the mask onto the substrate; a driving unit (RST, WST, 80, 34, 62) which synchronously moves the mask and the substrate at a velocity ratio corresponding to a magnification of the projection optical system; and an adjusting unit (80, RIFZ, 34, RST) which adjusts, during the synchronous movement, at least one of a position of the mask in a direction perpendicular to an object plane of the projection optical system and an inclination of the mask relative to the object plane.
According to the exposure apparatus concerning the seventh aspect, the illumination light beam is radiated from the illumination optical system obliquely with respect to the pattern plane of the mask. The illumination light beam from the illumination optical system is radiated in the oblique direction with respect to the pattern plane of the mask. The illumination light beam is reflected by the mask surface, and the reflected light beam is projected onto the substrate by the aid of the projection optical system. Thus, the pattern on the mask illuminated with the illumination light beam is transferred onto the substrate. During the transfer of the mask pattern, the driving unit is operated to synchronously move the mask and the substrate at the velocity ratio corresponding to the magnification of the projection optical system. During the synchronous movement, the adjusting unit is operated to adjust at least one of the position of the mask in the direction perpendicular to the object plane of the projection optical system and the relative inclination of the mask with respect to the object plane. Accordingly, the entire surface of the pattern on the mask is successively transferred onto the substrate in accordance with the scanning exposure. During this process, at least one of the position of the mask in the direction perpendicular to the object plane of the projection optical system and the relative inclination of the mask with respect to the object plane is adjusted by the aid of the adjusting unit. Therefore, it is possible to effectively suppress the occurrence of the magnification error or the distortion in the transferred image of the pattern on the substrate due to the inclination or the displacement of the mask in the direction of the optical axis. As a result, it is possible to improve the overlay accuracy.
According to an eighth aspect of the present invention, there is provided an exposure apparatus for transferring a pattern formed on a mask onto a substrate (W) by irradiating the mask (R) with an illumination light beam (EL), the exposure apparatus comprising a projection optical system which has a reflecting optical system composed of a plurality of mirrors (M1 to M4) and which projects the pattern onto the substrate by the aid of the reflecting optical system; and a cooling unit (HP, 52) arranged in a non-irradiated area on a reflecting surface of at least one mirror of the plurality of mirrors.
The invention according to the eighth aspect has been made taking notice of the fact that the cooling unit can be arranged on the reflecting surface provided that the area is not irradiated with the illumination light beam, because the illumination light beam is radiated only a part of the reflecting optical element in the exposure apparatus based on the use of the cata-dioptric system or the exposure apparatus based on the use of the reflecting optical system as the projection optical system as in the EUV exposure apparatus.
The exposure apparatus described above comprises the cooling unit which is arranged in the non-irradiated area of the illumination light beam on the reflecting surface of at least one mirror of the plurality of mirrors for constructing the projection optical system. Therefore, the reflecting surface is directly cooled so as not to cause the temperature change exceeding the limit. Accordingly, it is possible to avoid the deterioration of the image formation characteristic of the projection optical system due to the irradiation with the illumination light beam. As a result, it is possible to suppress the deterioration of the transferred image due to the variation of radiation.
The at least one mirror may be composed of a material having a relatively small coefficient of thermal conductivity. For example, the at least one mirror may be composed of a material having a coefficient of thermal conductivity of 5.0 W/mxc2x7K. When the mirror is composed of the material having the small coefficient of thermal conductivity, the deformation of the mirror due to the thermal conduction is suppressed even if the temperature is considerably changed. Accordingly, it is possible to avoid the deterioration of the image formation characteristic. Those preferably usable as the material for constructing the mirror include, for example, Zerodua (trade name) as low expansion glass (coefficient of thermal conductivity: 1.6 W/mxc2x7K) available from Shot, and ULE (trade name) available from Corning. In this arrangement, it is of course allowable that the other mirrors formed of a material having a large coefficient of thermal conductivity are cooled from the back surface side in the same manner as performed in the conventional technique. In this arrangement, it is also allowable that the cooling unit is also arranged on the back surface side of the mirror for which the cooling unit is arranged on the reflecting surface.
According to a ninth aspect of the present invention, there is provided an exposure apparatus for transferring a pattern formed on a mask onto a substrate (W) via a projection optical system (PO) by irradiating the mask (R) with an illumination light beam (EL), the exposure apparatus comprising a reflecting optical system composed of a plurality of mirrors (M1 to M4) including a first mirror (M1) and a second mirror (M2) to be successively irradiated with the illumination light beam, the reflecting optical system being used as the projection optical system; a body tube-cooling unit (52) which cools a body tube (PP) that holds the plurality of mirrors; and a heat exchanger (HP) provided between the body tube and at least one mirror of the plurality of mirrors.
According to the exposure apparatus concerning this aspect, the body tube for holding the plurality of mirrors is cooled by the body tube-cooling unit. When the temperature is raised in the plurality of mirrors by being irradiated with the illumination light beam, then the heat exchange is performed between the body tube and at least one mirror of the plurality of mirrors by the aid of the heat exchanger, and the mirror is forcibly cooled. The heat exchange by the heat exchanger is continuously performed during the radiation of the illumination light beam onto the mirror. Therefore, it is possible to avoid the deformation of the mirror connected with the heat exchanger, and it is possible to avoid the deterioration of the image formation characteristic of the projection optical system. As a result, it is possible to suppress the deterioration of the transferred image due to the variation of radiation. In this context, it is of course preferable that the heat exchangers are provided between the body tube and all of the mirrors held by the body tube so as to avoid the thermal deformation of all of the mirrors. Alternatively, the heat exchanger may be connected only to the first mirror which is firstly irradiated with the illumination light beam. Further alternatively, the heat exchanger may be connected to the second mirror in addition to the first mirror. The thermal energy of the illumination light beam is maximum at the position of the first mirror. Therefore, it is desirable that the heat exchanger is provided at least between the first mirror and the body tube to forcibly cool the first mirror.
In the exposure apparatus according to the ninth aspect, it is allowable that the body tube is composed of a plurality of divided body tubes (PP, PPxe2x80x2) which hold at least one mirror respectively; the body tube-cooling unit independently cools the respective divided body tubes; and at least one heat exchanger (HP) is provided between at least one mirror held by the divided body tube and each of the divided body tubes. In this arrangement, the body tube-cooling unit cools each of the divided body tubes in an independent manner. Therefore, the respective divided body tubes can be cooled at different cooling temperatures. As a result, the heat exchangers, which are provided between the respective divided body tubes and the mirrors held thereby, can be used to forcibly cool the mirrors concerning the respective divided body tubes up to the different temperatures. In this arrangement, it is desirable that one of the plurality of divided body tubes is the divided body tube (PPxe2x80x2) which holds the first mirror (M1) to be firstly irradiated with the illumination light beam (EL); one of the heat exchangers is provided between the first mirror and the divided body tube which holds the first mirror; and the body tube-cooling unit cools the divided body tube which holds the first mirror at a temperature lower than those for the other divided body tubes. By doing so, it is possible to efficiently cool the first mirror which absorbs the largest amount of heat and which tends to cause the deterioration of the image formation characteristic, as compared with the other mirrors. As a result, it is possible to efficiently suppress the deterioration of the transferred image due to the variation of radiation.
The heat exchanger may be anyone provided that it performs the heat exchange between the body tube (or the divided body tube) and the mirror. For example, the heat exchanger may be a heat pipe (HP). In this arrangement, as described in a specified embodiment, the front surface and the back surface of the mirror can be interposed by the heat pipe (HP) so that the light irradiation area on the front surface (reflecting surface) of the mirror, which is intended to be cooled, is not covered with the heat pipe (HP).
In the exposure apparatuses according to the eighth and ninth aspects, it is also preferable that the mask (R) is a reflecting type mask; and the apparatus further comprises a second cooling unit (36) arranged on a side opposite to an incoming side of the illumination light beam of the mask. In this arrangement, it is also possible to suppress the variation of radiation on the mask. Therefore, it is possible to more effectively suppress the deterioration of the transferred image due to the variation of radiation.
According to a tenth aspect of the present invention, there is provided an exposure apparatus having an illumination optical system (PRM, IM, 30, M, 42) for radiating an illumination light beam (EL) onto a mask (R), for transferring a pattern formed on the mask onto a substrate (W), the exposure apparatus comprising a projection optical system (PO) which has a reflecting optical element (M1 to M4) and which projects the illumination light beam outgoing from the mask onto the substrate; and a heat exchanger (HP) provided between the reflecting optical element and a body tube (PP) which holds the reflecting optical element.
The exposure apparatus according to this aspect is provided with the heat exchanger which is disposed between the reflecting optical element for constructing the projection optical system and the body tube for holding the reflecting optical element. Accordingly, when the illumination light beam outgoing from the mask is radiated onto the reflecting optical element, and the temperature of the reflecting optical element is raised, then the heat exchange is effected by the heat exchanger between the reflecting optical element and the body tube, and the reflecting optical element is cooled. The heat exchange, which is effected by the heat exchanger, is performed until the temperature of the reflecting optical element is coincident with that of the body tube. Therefore, it is possible to avoid, to some extent, the deterioration of the image formation characteristic of the projection optical system due to the radiation of the illumination light beam, by previously cooling the body tube. As a result, it is possible to suppress the deterioration of the transferred image due to the variation of radiation.
In the exposure apparatus according to the tenth aspect, it is also preferable that the heat exchanger is connected to at least one of a part of a reflecting surface of the reflecting optical element and a back surface thereof. It is of course allowable that the projection optical system may be a cata-dioptric system having a refracting optical element, other than the reflecting optical element. It is also preferable that the projection optical system is composed of only a plurality of reflecting optical elements, and at least one of the plurality of reflecting optical elements is connected to the heat exchanger. In this arrangement, it is desirable that the reflecting optical element (M1) of the plurality of reflecting optical elements, which has the shortest optical distance with respect to the mask, is connected to the heat exchanger (HP). In this arrangement, it is possible to cool the reflecting optical element which has the largest amount of heat absorption and which tends to cause the deterioration of the image formation characteristic, because the optical distance with respect to the mask is shortest. As a result, it is possible to efficiently suppress the deterioration of the transferred image due to the variation of radiation.
In the exposure apparatuses according to the eighth to tenth aspects provided with the heat exchanger, it is also preferable that the projection optical system is an optical system which has a ring image field, which is non-telecentric on a side of an object plane, and which is telecentric on a side of an image plane. In the exposure apparatuses according to the eighth to tenth aspects, it is also preferable that the illumination light beam is an EUV light beam having a wavelength of 5 to 15 nm, because of the following reason. That is, the illumination light beam having the short wavelength such as the EUV light beam has the large radiation energy, for which it is more necessary to cool the mirror or the reflecting optical element.
According to an eleventh aspect of the present invention, there is provided a method for producing an exposure apparatus for transferring a pattern formed on a reflecting type mask onto a substrate, the method comprising the steps of:
providing a projection optical system provided with a reflecting optical system which projects the pattern onto the substrate;
providing a mask stage which holds the mask;
providing a substrate stage which holds the substrate;
providing an illumination system which radiates an exposing illumination light beam onto the mask at a predetermined angle of incidence with respect to a pattern plane of the mask; and
providing a stage control system which synchronously moves the mask stage and the substrate stage in a second axis direction perpendicular to a first axis direction, while adjusting a position of the mask in the first axis direction as a direction of an optical axis of the projection optical system, on the basis of predetermined adjusting position information, in order to transfer the pattern on the mask illuminated with the exposing illumination light beam onto the substrate via the projection optical system.
According to a twelfth aspect of the present invention, there is provided a method for producing an exposure apparatus for transferring a pattern on a mask onto a substrate, the method comprising the steps of:
providing an illumination optical system which has an optical axis inclined with respect to a first direction perpendicular to the mask and which radiates an illumination light beam onto the mask;
providing a projection optical system which projects, onto the substrate, the illumination light beam reflected by the mask;
providing a driving unit which synchronously moves the mask and the substrate at a velocity ratio corresponding to a magnification of the projection optical system; and
providing a correcting unit which corrects an image magnification error of the pattern by relatively moving the mask in the first direction with respect to the projection optical system during the synchronous movement.
According to a thirteenth aspect of the present invention, there is provided a method for producing an exposure apparatus for transferring a pattern on a mask onto a substrate, the method comprising the steps of:
providing an illumination optical system which radiates, onto the mask, an illumination light beam having a main light beam which is inclined with respect to a first direction perpendicular to the mask;
providing a projection optical system which projects, onto the substrate, the illumination light beam outgoing from the mask;
providing a driving unit which synchronously moves the mask and the substrate at a velocity ratio corresponding to a magnification of the projection optical system; and
providing a correcting unit which compensates change in image magnification of the pattern caused by the movement of the mask.
According to a fourteenth aspect of the present invention, there is provided a method for producing an exposure apparatus for transferring a pattern on a mask onto a substrate, the method comprising the steps of:
providing an illumination optical system which radiates, onto the mask, an illumination light beam inclined with respect to a perpendicular line of the mask; and
providing a projection optical system which projects, onto the substrate, the illumination light beam reflected by the mask, wherein:
the illumination optical system has a field diaphragm which is arranged closely to an incoming side of the illumination light beam with respect to the mask and which defines an irradiated area of the illumination light beam on the mask, and the field diaphragm is used to adjust at least one of a shape, a size, and a position of the illumination area.
According to a fifteenth aspect of the present invention, there is provided a method for producing an exposure apparatus for transferring a pattern on a mask onto a substrate, the method comprising the steps of:
providing an illumination optical system which obliquely radiates an illumination light beam onto a pattern plane of the mask;
providing a projection optical system which projects the illumination light beam outgoing from the mask onto the substrate;
providing a driving unit which synchronously moves the mask and the substrate at a velocity ratio corresponding to a magnification of the projection optical system; and
providing an adjusting unit which adjusts, during the synchronous movement, at least one of a position of the mask in a direction perpendicular to an object plane of the projection optical system and a relative inclination of the mask with respect to the object plane.
According to a sixteenth aspect of the present invention, there is provided a method for producing an exposure apparatus for transferring a pattern formed on a mask onto a substrate by irradiating the mask, the method comprising the steps of:
providing a projection optical system which has a reflecting optical system composed of a plurality of mirrors and which projects the pattern onto the substrate; and
providing a cooling unit which cools at least one mirror of the plurality of mirrors so that the cooling unit is arranged in a non-irradiated area of a reflecting surface of the at least one mirror.
According to a seventeenth aspect of the present invention, there is provided a method for producing an exposure apparatus for transferring a pattern formed on a mask onto a substrate via a projection optical system by irradiating the mask, the method comprising the steps of:
providing a reflecting optical system composed of a plurality of mirrors including a first mirror and a second mirror to be successively irradiated with an illumination light beam, the reflecting optical system being used as the projection optical system;
providing a body tube-cooling unit which cools a body tube that holds the plurality of mirrors; and
providing a heat exchanger disposed between the body tube and at least one mirror of the plurality of mirrors.
According to an eighteenth aspect of the present invention, there is provided a method for producing an exposure apparatus for transferring a pattern formed on a mask onto a substrate, the method comprising the steps of:
providing an illumination optical system which radiates an illumination light beam onto the mask;
providing a projection optical system which has a reflecting optical element and which projects the illumination light beam outgoing from the mask onto the substrate; and
providing a heat exchanger disposed between the reflecting optical element and a body tube which holds the reflecting optical element.
According to a nineteenth aspect of the present invention, there is provided a microdevice produced by the exposure apparatus according to the aspects of the present invention described above.
According to a twentieth aspect of the present invention, there is provided a microdevice produced by the exposure method according to the aspects of the present invention described above.